Tone-arm



J. W. BOOTH.

TONE ARM.

APPLICATION F|LEDmAR.l0,192o.-

1, 385,358. PamdJulyzalsm,

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TONE ARM.

APPLICATION FiLED MAR10| 1920.

1,385,358. Patented July 26,1921;

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PATENT OFFICE.

JOHN WESLEY BOOTH, or TRENTON, ONTARIO, CANADA.

TONE-ARM Application led March 10, 1920.

T all whom t may concern: i

Be it known that I, JOHN W. BOOTH, a citizen of the United States of America, and resident of the town of Trenton, in the county of Hastings, Province of Ontario, Dominion of Canada, have invented certain new and useful Improvements in Tone- Arms, of which the following is a specification.

This invention relates to improvements in tone arms for sound reproducing machines, and the objects of the invention are to provide a simple and effective tone arm in which the tone passage will be free from obstruction, and may be freely supported to enable it to perform effectively the functions required of it, and move ovler the record.

More specific objects are to provide an improved form of spring support for the tone arm and. an improved joint between the tone arm and base, which will'avoid any interference with sound rays passing through the tone arm.

Still further objects are to obtain mellowness of tone, freedom from unnecessary vibration and smoothness of action on the record.

The invention consists essentially of the improved construction, hereinafter described in detail in the accompanying specification and drawings;

In the drawings;

Figure 1 is a sectional elevation showing an embodiment of my invention.

Fig. 2 is an end elevation.

Fig. 3 is a sectional plan taken on the line m--m of Fig. 1.

Fig. 4; is a detail sleeve containing a supporting spring.

In the drawings, like characters of refer ence indicate corresponding parts in all the figures. A

Referring to the.drawings, A indicates the motor board, and B the tone arm, which is pivotally mounted with freedom to turn about a vertical axis, and a supporting sleeve C, the end of the tone arm being formed with a ball 10, which fits the socket 11 in the sleeve, and a pivotal pin 12 connecting the tone arm and socket.

The sleeve C is formed with a projecting annular flange 14 extending over the inside of the bearing member D, and constitutes the tone passage 13.

To prevent escaping of tone between the Specification of Letters Patent.

. members.

Patented July 26', 1921.

Serial No. 364,707.

members D and C I preferably provide a felt lining or packing 15, between the two The return movement between the two members D and C is limited by means of a spring plunger 16 mounted in a recess 17 in the member C and engaging arcuate slots 18 in the member D.

Spring support is given to the tone arm by means of a spiral compression spring 18 contained within a sleeve 19 supported from a bracket 20 connected to the member C.

The spring 18 presses at opposite ends against plungers 21 and 22 which it the sleeve, movement of the plungers being limited by pins 23 and 24: thereon, which Operate in slots 25 and 26. The slot 25 is formed with one lateral slot or step 27, while the slot 26 is formed with three lateral slots or steps 28 and 29 and 30.

It will be seen that by adjusting the plungers 2l and 22 by engaging the pin 211 with either one of the slots or steps 28, 29 or 30. The tension of the spring 1S may be adjusted the same way at the upper end. The tension on the tone arm might be released by moving the plunger downwardly and engaging the pin 23 with the slot or step 27.

The plunger 21 is conveniently formed with a round end, and will engage a bearing plate 31 on the tone arm.

It is seen that the foregoing provides simple and effective means of adjusting the spring supporting pressure on the tone arm. This is accomplished without any interfer- Vence with the tone passage, which is quite free from obstruction. This taken with the tight joint produced by the felt packing 15, and the general construction of the member C enables the remarkable mellowness of tone to be produced, together with freedom from unnecessary vibration and smoothness in action on the record.

The tone arm may be formed of wood or metal or other convenient material, such as rubber composition. or the like.

As many changes could be made in the above construction, and many apparently widely different embodiments of my inven tion, within the scope of the claims, constructed without departing from the spirit or scope thereof, it is intended that all matter contained in the accompanying specification and drawings shall be interpreted as illustrative, and not in a limiting sense.

What I claim as my invention is 1. A resilient support for pivotally mounted tone arms, comprising a cylinder, a plunger slidably mounted in one end of said cylinder to project therefrom, a plug closing the opposite end of said cylinder and slidably mounted therein, a plunger projecting Aspring conned between said plunger and plug, said plug being slidable in the cylinder relative to the plunger to vary the tension of the intervening spring, and cooperating means carried by said plug and cylinder for supporting the plug in the cylinder and locln'ng it in adjusted position therein.,

2. In a device of the character described, aV tone f arm having a downwardly turned inner end, a sleeve pivotally connected to the tone arm, a bracket connected to the outer side of the sleeve and extending outwardly therefrom, a vertically extending Vsleeve carried by the bracket, a spring therein, and a 20 means for limiting the outward movement 30 of said plunger, and locking the plunger in retracted position.

In witness whereof I have hereunto set my hand in the oresence of two witnesses. JO IN WESLEY BOOTH. Witnesses JOHN LAINARD, THOMAS ALFRED OROURKE. 

